The Canon Cinema EOS (Cinema Electro-Optical System) autofocus digital photographic and cinematographic SLR and mirrorless interchangeable lens camera system was introduced in late 2011 with the Canon EOS C300 and followed by the Canon EOS C500 and Canon EOS 1D C in early 2012. Cinema EOS is a branch off from the existing EOS line of cameras that date back to 1987 with the introduction of the analog Canon EOS 650. With many Canon DSLRs adding motion video capabilities starting with the Canon EOS 5D Mark II in 2008, Canon decided to focus on making cameras specially designed for motion video instead of just producing still video cameras with some motion video capabilities. The Cinema EOS line started in late 2011, with the introduction of the C300, a motion video camera with a mirrorless design and Super 35 sensor, and new CN-E lenses (with both Canon EF and Arri PL mounts). The announcement also unveiled an upcoming Canon camera that would feature 4K motion video capabilities in a DSLR body.
The demonstration of a prototype device from Canon was a rarity and was seen as a sign of their intent to enter the new still and motion camera market. In early 2012, Canon began to expand the Cinema EOS line with the C500, which added 4K/QHD recording and RAW capture to the existing features of the C300. The new C500 would be the first camera to offer uncompressed raw motion video recording. Canon also announced a variant of the Canon EOS-1D X, called the Canon EOS-1D C, which featured 4K (but not raw) recording on the same sensor. The new split in the Canon EOS 1D series follows its recent reunification of the high resolution line (1D S) and high speed line (1D) in 2011.